An 88kg shipment of ice, heroin and opium is also believed to have been missed by Melbourne customs officers despite the pallet they were hidden on being X-rayed, a Herald Sun investigation has discovered.

The shipments by air and sea are revealed in "missed detection" reports obtained from the Australian Customs and Border Protection Service by the Herald Sun under Freedom of Information laws.

Missed detections are reported when illegal shipments of guns, drugs and other contraband are detected after passing through customs, usually by police.

The missed firearms deliveries included a "large cache" of up to 220 Glock and Taurus handguns, imported on forged papers in up to 20 shipments of parts from Germany.

Police allege the import of guns in parts were specifically for use by criminal gangs.

The racket was discovered after police traced a number of weapons seized during investigations into a string of armed robberies.

Strike Force Maxworthy detectives determined the weapons came from the same batch manufactured in Austria just three months earlier and allegedly imported via a German firearms dealership using forged documentation.

In March last year, 12 simultaneous raids in NSW led to the arrest and charging of a 30-year-old post office licensee, a 21-year-old import business employee and a 27-year-old telecommunications technician, and the seizing of seven firearms, ammunition, small quantities of steroids and prohibited drugs, numerous mail items, documents and computer equipment. A German man was arrested in Remscheid, Germany, with 20 Glock pistols also destined for Australia.

A parcel containing 140 Glock brand magazines and a quantity of speedloaders was also discovered after the raids when customs air cargo officers acting on a tip off from police searched a package declared as "plastic items".

Subsequent Customs checks revealed about 20 similar packages had previously been successfully imported and delivered.

The matter is now before the courts in NSW.

Speaking at the launch of a new Customs blueprint in July, former Federal Justice Minister Jason Clare conceded law enforcement agencies needed better information to counter the trade in illegally imported guns by motorcycle gangs and other criminals.

The Abbott Government has promised a $100 million boost to Customs screening in a bid to reduce illegal guns and drugs "flooding onto our streets".

New Justice Minister Michael Keenan told the Herald Sun intelligence was vital to combating organised crime and was why the Government had also established a national anti-gang squad, that will see federal law agencies, including the Australian Crime Commission and the Australian Federal Police work with local police, and toughened unexplained wealth laws.

"This will give the state police forces access to the extensive national criminal intelligence databases used by the ACC and AFP," he said.

New Justice Minister Michael Keenan told the Herald Sun intelligence was vital to combating organised crime and this was why the Government had also established a national anti-gang squad, which would see federal law agencies, including the Australian Crime Commission and the Australian Federal Police work with local police, and toughened unexplained wealth laws.

"This will give the state police forces access to the extensive national criminal intelligence databases used by the ACC and AFP," he said